I don't have my stirrups that short for jumping, because my leg does exactly the same as yours if it is too short. Lengthen them a hole maybe because your leg does not look natural, and it seems you have to push your lower leg back and down in order to get your heel down too. If that makes sense. Actually, in the videos it looks better. It might just look awkward in the photos haha. Also, your toes point a bit too far out for my liking, work on pushing them straight, but slightly turned out :)
Your seat is lovely though, but like people have said before me you round your shoulder a little bit. Sit tall!
This is how I personally like to see someones position, people will probably disagree with me about some bits, haha.